I have the Alpha 40 DSM II version, and the rubber band arrangement is seriously strong. I use a criss-cross with 2 bands, then 3 each side, then another 2 for criss-cross. Never had any kind of issues. As suggested above, go to Staples of OfficeMax, whatever, and buy a big bag cheap. I usually replace them after 2-3 days use or so but will toss them at the end of the day if they've gotten slimed badly.

As a testament to how strong this arrangement is, I tried to make the field wider by about 18 inches one day with the Alpha. The wing clipped a tree and brought the plane down fast. I lost the 18 inches of wing but it stayed attached after the fall. The area of the Fuse behind the wing buckled some but the wing stayed put.

Bottom line, no worries with the rubber bands if you pay attention and make sure they're fresh.